This invention relates to a fireproof panel for incorporation in a fireproof bulkhead which is for separating an area to be protected from an area in which there is a fire risk. Such a bulkhead has particular, but not exclusive, application in a vehicle wherein the area to be protected may be a driver's compartment, an electronics equipment compartment or a fire escape route and the fire risk may arise from an engine, or from electrical equipment such as a cable, a motor or a transformer. Alternative applications to which the invention relates may include oil platforms and similar structures.

If a conventional material, such as a mineral wool or a similar mass of ceramic fibres, is incorporated in a fireproof bulkhead in order to prevent air from being moved so that that air acts as an insulant across the area of the bulkhead, that bulkhead occupies a considerable amount of space. That is to say it is bulky which is undesirable because weight and cost increase with bulk.

An object of this invention is to enable a fireproof bulkhead to be constructed which is thin and lightweight compared to a bulkhead construction using mineral wool or ceramic fibres .

According to this invention there is provided a fireproof panel which comprises ceramic material wherein each fixing means by which the panel is fixed to structure of the bulkhead when it is

incorporated therein, is surrounded by a rigid ceramic material having a low thermal conductivity which is incorporated in the fireproof panel.

Preferably the rigid ceramic material of low thermal conductivity has endothermic properties. There may be a thin coating of an endothermic mastic between the fixing means and the surrounding rigid ceramic material.

According to a feature of this invention there is provided a fireproof bulkhead which comprises a framework of structural members which is sandwiched between sheet material which forms a wall surface of an area to be protected from fire and a fireproof panel in which this invention is embodied and which is fixed to the framework by such fixing means, and the remainder of the framework on the side of the bulkhead that is remote from said wall surface is lined by a ceramic mat material which is also incorporated in the fireproof panel and which is bonded to the framework by a thin coating of an endothermic mastic.

Preferably the rigid ceramic material having a low thermal conductivity comprises flat gaskets which are fixed at spaced locations to respective frame elements of the framework as well as being bonded to the respective frame elements by the endothermic mastic which also surrounds the fixing means, each gasket being surrounded by said ceramic mat material which is not so highly endothermic as the material of the gaskets but which is also intumescent.

One embodiment of this invention is described now by way of example with reference to the accompanying drawings, of which:-

Figure 1 is a fragmentary front elevation of a fireproof bulkhead with sheet material surface layers partly cutaway to reveal hidden detail;

Figure 2 is a fragmentary section on the line A-A in Figure 1;

Figure 3 is an isometric view of a fragment of the bulkhead shown in Figure 1 with part of the surface layers cutaway;

Figure 4 is an elevation of a fireproof panel for incorporation in a fireproof bulkhead and constructed in a similar manner to the bulkhead shown in Figure 1; and

Figure 5 is a section on the line B-B in Figure 4.

Figures 1 to 3 show the bulkhead construction comprises a sheet metal panel 10 which forms a wall surface of an area 11 which is to be protected from fire, such as a driver's compartment of a locomotive or a compartment in which electronics equipment is house .

The panel 10 is reinforced by a structural framework 13 of box section steel pillars and beams which are outside the area 11. Conveniently each pillar and beam comprises a top-hat section metal extrusion which is fixed, say by rivets, at spaced intervals through its flanges. The framework 13 is sandwiched between the panel 10 and a fireproof panel 14.

The fireproof panel 14 comprises gaskets 15 of an endothermic ceramic material (such as 'Interam E5A' material marketed by the 3M company), which are clamped at spaced locations to the pillars and beams of the framework 13 by a convenient fixing arrangement with a thin layer of an endothermic ceramic mastic material (which is not shown but which may be 'Firedam 150' mastic marketed by the 3M company) between them and the pillars and beams to which they are fixed. The fireproof panel 14 also comprises strips 16 and a sheet 17 which are formed of a felt¬ like mat of a fibrous intumescent ceramic material on an aluminium foil backing sheet to which it is fixed. The intumescent ceramic material has poor endothermic properties compared with those of the material of the gaskets 15 which is relatively incompressible. The fibres from which the felt-like ceramic material are formed are retained within that material by the nature of its formation. They would not be released if the material were to be cut. A suitable material for use as the material of the strips 16 and the sheet 17 is 'Interam 110 A ¹ material marketed by the 3M company. The strips 16 and the sheet 17, which, in their natural relaxed state, are about half as thick as the gaskets 15, are orientated so that, in each case, the aluminium foil backing sheet 17A is further from the panel 10 than is the ceramic mat material. The strips 16 line the portions of the top of each of the top-hat section beams and pillars that extend between the gaskets 15, being bonded thereto by a thin layer of the endothermic ceramic mastic material (not

shown) which infiltrates the mat material. The fireproof panel 14 is completed by an outer sheet 18 of perforated steel and an inner wire mesh retainer 19 which lines the side of the sheet 17 adjacent the panel 10 and surrounds the gaskets 15, and thereby provides structural support for the ceramic mat material of the sheet 17.

Conveniently the fixing arrangement by which the fireproof panel 14 is clamped to the beams and pillars at spaced locations is of the kind known as a 'rivnut' which comprises a nut formed integrally with the head of a rivet so that the nut portion provides an anchorage for a bolt or a setscrew when it is fixed to structure, in this case the top of the top-hat section beam or pillar, by rivetting the rivet portion to that structure. Each gasket 15 has a central through hole 21 and is seated on the top of the top hat section beam or pillar to which it is clamped in line with the nut portion 22 of a respective one of the fixing arrangements 23 which is fixed to the beam or pillar by rivetting.

The gaskets 15, and thus the fireproof panel 14, are clamped to the framework 13 by bolts or setscrews 24 which are inserted through appropriate holes 25 in the outer sheet 18 and through the central hole 21 of the respective gasket 15 and which are screwed into the anchorage 22. Holes 26 formed in the sheet 17 are similar in size and shape to the perimeter of the respective gasket 15 so that the sheet 17 fits around the gaskets 15. Alternatively the material of the sheet 17 may compressed between the outer sheet 18 and the gaskets 15.

The spaces around the pillars and beams of the framework 13 and between the panel 10 and the 16 may be filled with mineral wool or a fibrous ceramic material.

Heat transfer through the fireproof panel 14 to the structure formed by the framework 13 and the panel 10, via the bolts or setscrews 24, is minimised by the endothermic action of the material of the gaskets 15 and of the thin mastic layer by which they are bonded to the framework 13. That heat protection is complemented by the intumescent action of the ceramic mat material of the strips 16 and the sheet 17 and by the radiant heat reflecting characteristics of its aluminium foil backing sheet. The latter is particularly significant since, at temperatures of the order of 400-500 degrees Celsius or more, heat radiation is the dominant form of heat transfer rather than conduction or convection. Radiant heat is also absorbed by the ceramic materials of the gaskets 15, the strips 16 and the sheet 17. Also any steam released by the endothermic action of the endothermic materials due to heating, which gathers in the spaces around the beams and pillars of the framework 13 between the panel 10 and the fireproof panel 14 further assists in providing a thermal barrier.

That the mastic material is an effective means of bonding the strips 16 to the framework 13 is a surprise, since it would have been expected to crack up at the high temperatures to which it would be subjected in the event of a fire. The explanation is

that it is used thinly, much more thinly than when it is used as a caulking material which is the use for which it was intended and for which it is marketed.

Instead of being formed of an endothermic ceramic material, in some applications the gaskets 15 may be formed of a high- temperature ceramic such as may be obtained from Morgan Matrock Limited or of 'Synolite' a glass-fibre reinforced resin obtainable from British Mica Co.Ltd. Another layer of aluminium foil may be provided on the side of the layer 17 adjacent the sheet metal panel 10.

Figures 4 and 5 show that a smaller fireproof panel structure may be constructed similarly to the bulkhead described with reference to and as illustrated in Figures 1,2 and 3. It is rectangular and is provided with a peripheral frame 27 which is formed of a sheet metal strip bent around the edge of the panel structure.